--
-----------------------------------------------------------------------------
-#include "config.h"
+#include "ghcconfig.h"
module GHC.Conc
( ThreadId(..)
#endif
) where
+import System.Posix.Types
+import System.Posix.Internals
+import Foreign
+import Foreign.C
+
import Data.Maybe
import GHC.Base
-import GHC.IOBase ( IO(..), MVar(..), ioException, IOException(..), IOErrorType(..) )
-import GHC.Num ( fromInteger, negate )
-import GHC.Real ( fromIntegral )
+import GHC.IOBase
+import GHC.Num ( Num(..) )
+import GHC.Real ( fromIntegral, quot )
import GHC.Base ( Int(..) )
import GHC.Exception ( Exception(..), AsyncException(..) )
import GHC.Pack ( packCString# )
import GHC.Ptr ( Ptr(..), plusPtr, FunPtr(..) )
+import GHC.STRef
infixr 0 `par`, `pseq`
\end{code}
-- 'putMVar' will wait until it becomes empty.
--
-- If several threads are competing to fill the same 'MVar', one is
--- chosen to continue at random with the 'MVar' becomes empty.
+-- chosen to continue at random when the 'MVar' becomes empty.
putMVar :: MVar a -> a -> IO ()
putMVar (MVar mvar#) x = IO $ \ s# ->
case putMVar# mvar# x s# of
%* *
%************************************************************************
-@threadWaitRead@ delays rescheduling of a thread until input on the
-specified file descriptor is available for reading (just like select).
-@threadWaitWrite@ is similar, but for writing on a file descriptor.
-
\begin{code}
--- | Suspends the current thread for a given number of microseconds
--- (GHC only).
---
--- Note that the resolution used by the Haskell runtime system's
--- internal timer is 1\/50 second, and 'threadDelay' will round its
--- argument up to the nearest multiple of this resolution.
---
--- There is no guarantee that the thread will be rescheduled promptly
--- when the delay has expired, but the thread will never continue to
--- run /earlier/ than specified.
---
-threadDelay :: Int -> IO ()
-
--- | Block the current thread until data is available to read on the
--- given file descriptor (GHC only).
-threadWaitRead :: Int -> IO ()
-
--- | Block the current thread until data can be written to the
--- given file descriptor (GHC only).
-threadWaitWrite :: Int -> IO ()
-
-threadDelay (I# ms) = IO $ \s -> case delay# ms s of s -> (# s, () #)
-threadWaitRead (I# fd) = IO $ \s -> case waitRead# fd s of s -> (# s, () #)
-threadWaitWrite (I# fd) = IO $ \s -> case waitWrite# fd s of s -> (# s, () #)
-
#ifdef mingw32_TARGET_OS
-- Note: threadDelay, threadWaitRead and threadWaitWrite aren't really functional
asyncWrite fd isSock len ((Ptr (byteArrayContents# (unsafeCoerce# bufB))) `plusPtr` off)
#endif
+
+-- -----------------------------------------------------------------------------
+-- Thread IO API
+
+-- | Block the current thread until data is available to read on the
+-- given file descriptor (GHC only).
+threadWaitRead :: Fd -> IO ()
+threadWaitRead fd
+#ifndef mingw32_TARGET_OS
+ | threaded = waitForReadEvent fd
+#endif
+ | otherwise = IO $ \s ->
+ case fromIntegral fd of { I# fd# ->
+ case waitRead# fd# s of { s -> (# s, () #)
+ }}
+
+-- | Block the current thread until data can be written to the
+-- given file descriptor (GHC only).
+threadWaitWrite :: Fd -> IO ()
+threadWaitWrite fd
+#ifndef mingw32_TARGET_OS
+ | threaded = waitForWriteEvent fd
+#endif
+ | otherwise = IO $ \s ->
+ case fromIntegral fd of { I# fd# ->
+ case waitWrite# fd# s of { s -> (# s, () #)
+ }}
+
+-- | Suspends the current thread for a given number of microseconds
+-- (GHC only).
+--
+-- Note that the resolution used by the Haskell runtime system's
+-- internal timer is 1\/50 second, and 'threadDelay' will round its
+-- argument up to the nearest multiple of this resolution.
+--
+-- There is no guarantee that the thread will be rescheduled promptly
+-- when the delay has expired, but the thread will never continue to
+-- run /earlier/ than specified.
+--
+threadDelay :: Int -> IO ()
+threadDelay time
+#ifndef mingw32_TARGET_OS
+ | threaded = waitForDelayEvent time
+#else
+ | threaded = c_Sleep (fromIntegral (time `quot` 1000))
+#endif
+ | otherwise = IO $ \s ->
+ case fromIntegral time of { I# time# ->
+ case delay# time# s of { s -> (# s, () #)
+ }}
+
+-- On Windows, we just make a safe call to 'Sleep' to implement threadDelay.
+#ifdef mingw32_TARGET_OS
+foreign import ccall safe "Sleep" c_Sleep :: CInt -> IO ()
+#endif
+
+foreign import ccall unsafe "rtsSupportsBoundThreads" threaded :: Bool
+
+-- ----------------------------------------------------------------------------
+-- Threaded RTS implementation of threadWaitRead, threadWaitWrite, threadDelay
+
+-- In the threaded RTS, we employ a single IO Manager thread to wait
+-- for all outstanding IO requests (threadWaitRead,threadWaitWrite)
+-- and delays (threadDelay).
+--
+-- We can do this because in the threaded RTS the IO Manager can make
+-- a non-blocking call to select(), so we don't have to do select() in
+-- the scheduler as we have to in the non-threaded RTS. We get performance
+-- benefits from doing it this way, because we only have to restart the select()
+-- when a new request arrives, rather than doing one select() each time
+-- around the scheduler loop. Furthermore, the scheduler can be simplified
+-- by not having to check for completed IO requests.
+
+-- Issues, possible problems:
+--
+-- - we might want bound threads to just do the blocking
+-- operation rather than communicating with the IO manager
+-- thread. This would prevent simgle-threaded programs which do
+-- IO from requiring multiple OS threads. However, it would also
+-- prevent bound threads waiting on IO from being killed or sent
+-- exceptions.
+--
+-- - Apprently exec() doesn't work on Linux in a multithreaded program.
+-- I couldn't repeat this.
+--
+-- - How do we handle signal delivery in the multithreaded RTS?
+--
+-- - forkProcess will kill the IO manager thread. Let's just
+-- hope we don't need to do any blocking IO between fork & exec.
+
+#ifndef mingw32_TARGET_OS
+
+data IOReq
+ = Read {-# UNPACK #-} !Fd {-# UNPACK #-} !(MVar ())
+ | Write {-# UNPACK #-} !Fd {-# UNPACK #-} !(MVar ())
+
+data DelayReq
+ = Delay {-# UNPACK #-} !Int {-# UNPACK #-} !(MVar ())
+
+pendingEvents :: IORef [IOReq]
+pendingDelays :: IORef [DelayReq]
+ -- could use a strict list or array here
+{-# NOINLINE pendingEvents #-}
+{-# NOINLINE pendingDelays #-}
+(pendingEvents,pendingDelays) = unsafePerformIO $ do
+ startIOServiceThread
+ reqs <- newIORef []
+ dels <- newIORef []
+ return (reqs, dels)
+ -- the first time we schedule an IO request, the service thread
+ -- will be created (cool, huh?)
+
+startIOServiceThread :: IO ()
+startIOServiceThread = do
+ allocaArray 2 $ \fds -> do
+ throwErrnoIfMinus1 "startIOServiceThread" (c_pipe fds)
+ rd_end <- peekElemOff fds 0
+ wr_end <- peekElemOff fds 1
+ writeIORef stick (fromIntegral wr_end)
+ quickForkIO $ do
+ allocaBytes sizeofFdSet $ \readfds -> do
+ allocaBytes sizeofFdSet $ \writefds -> do
+ allocaBytes sizeofTimeVal $ \timeval -> do
+ service_loop (fromIntegral rd_end) readfds writefds timeval [] []
+ return ()
+
+-- XXX: move real forkIO here from Control.Concurrent?
+quickForkIO action = IO $ \s ->
+ case (fork# action s) of (# s1, id #) -> (# s1, ThreadId id #)
+
+service_loop
+ :: Fd -- listen to this for wakeup calls
+ -> Ptr CFdSet
+ -> Ptr CFdSet
+ -> Ptr CTimeVal
+ -> [IOReq]
+ -> [DelayReq]
+ -> IO ()
+service_loop wakeup readfds writefds ptimeval old_reqs old_delays = do
+
+ -- pick up new IO requests
+ new_reqs <- atomicModifyIORef pendingEvents (\a -> ([],a))
+ let reqs = new_reqs ++ old_reqs
+
+ -- pick up new delay requests
+ new_delays <- atomicModifyIORef pendingDelays (\a -> ([],a))
+ let delays = foldr insertDelay old_delays new_delays
+
+ -- build the FDSets for select()
+ fdZero readfds
+ fdZero writefds
+ fdSet wakeup readfds
+ maxfd <- buildFdSets 0 readfds writefds reqs
+
+ -- check the current time and wake up any thread in threadDelay whose
+ -- timeout has expired. Also find the timeout value for the select() call.
+ now <- getTicksOfDay
+ (delays', timeout) <- getDelay now ptimeval delays
+
+ -- perform the select()
+ let do_select = do
+ res <- c_select ((max wakeup maxfd)+1) readfds writefds
+ nullPtr timeout
+ if (res == -1)
+ then do
+ err <- getErrno
+ if err == eINTR
+ then do_select
+ else return res
+ else
+ return res
+ res <- do_select
+ -- ToDo: check result
+
+ old <- atomicModifyIORef prodding (\old -> (False,old))
+ if old
+ then alloca $ \p -> do c_read (fromIntegral wakeup) p 1; return ()
+ else return ()
+
+ reqs' <- completeRequests reqs readfds writefds []
+ service_loop wakeup readfds writefds ptimeval reqs' delays'
+
+stick :: IORef Fd
+{-# NOINLINE stick #-}
+stick = unsafePerformIO (newIORef 0)
+
+prodding :: IORef Bool
+{-# NOINLINE prodding #-}
+prodding = unsafePerformIO (newIORef False)
+
+prodServiceThread :: IO ()
+prodServiceThread = do
+ b <- atomicModifyIORef prodding (\old -> (True,old)) -- compare & swap!
+ if (not b)
+ then do
+ fd <- readIORef stick
+ with 42 $ \pbuf -> do c_write (fromIntegral fd) pbuf 1; return ()
+ else
+ return ()
+
+-- -----------------------------------------------------------------------------
+-- IO requests
+
+buildFdSets maxfd readfds writefds [] = return maxfd
+buildFdSets maxfd readfds writefds (Read fd m : reqs) = do
+ fdSet fd readfds
+ buildFdSets (max maxfd fd) readfds writefds reqs
+buildFdSets maxfd readfds writefds (Write fd m : reqs) = do
+ fdSet fd writefds
+ buildFdSets (max maxfd fd) readfds writefds reqs
+
+completeRequests [] _ _ reqs' = return reqs'
+completeRequests (Read fd m : reqs) readfds writefds reqs' = do
+ b <- fdIsSet fd readfds
+ if b /= 0
+ then do putMVar m (); completeRequests reqs readfds writefds reqs'
+ else completeRequests reqs readfds writefds (Read fd m : reqs')
+completeRequests (Write fd m : reqs) readfds writefds reqs' = do
+ b <- fdIsSet fd writefds
+ if b /= 0
+ then do putMVar m (); completeRequests reqs readfds writefds reqs'
+ else completeRequests reqs readfds writefds (Write fd m : reqs')
+
+waitForReadEvent :: Fd -> IO ()
+waitForReadEvent fd = do
+ m <- newEmptyMVar
+ atomicModifyIORef pendingEvents (\xs -> (Read fd m : xs, ()))
+ prodServiceThread
+ takeMVar m
+
+waitForWriteEvent :: Fd -> IO ()
+waitForWriteEvent fd = do
+ m <- newEmptyMVar
+ atomicModifyIORef pendingEvents (\xs -> (Write fd m : xs, ()))
+ prodServiceThread
+ takeMVar m
+
+-- XXX: move into GHC.IOBase from Data.IORef?
+atomicModifyIORef :: IORef a -> (a -> (a,b)) -> IO b
+atomicModifyIORef (IORef (STRef r#)) f = IO $ \s -> atomicModifyMutVar# r# f s
+
+-- -----------------------------------------------------------------------------
+-- Delays
+
+waitForDelayEvent :: Int -> IO ()
+waitForDelayEvent usecs = do
+ m <- newEmptyMVar
+ now <- getTicksOfDay
+ let target = now + usecs `quot` tick_usecs
+ atomicModifyIORef pendingDelays (\xs -> (Delay target m : xs, ()))
+ prodServiceThread
+ takeMVar m
+
+-- Walk the queue of pending delays, waking up any that have passed
+-- and return the smallest delay to wait for. The queue of pending
+-- delays is kept ordered.
+getDelay :: Ticks -> Ptr CTimeVal -> [DelayReq] -> IO ([DelayReq], Ptr CTimeVal)
+getDelay now ptimeval [] = return ([],nullPtr)
+getDelay now ptimeval all@(Delay time m : rest)
+ | now >= time = do
+ putMVar m ()
+ getDelay now ptimeval rest
+ | otherwise = do
+ setTimevalTicks ptimeval (time - now)
+ return (all,ptimeval)
+
+insertDelay :: DelayReq -> [DelayReq] -> [DelayReq]
+insertDelay d@(Delay time m) [] = [d]
+insertDelay d1@(Delay time m) ds@(d2@(Delay time' m') : rest)
+ | time <= time' = d1 : ds
+ | otherwise = d2 : insertDelay d1 rest
+
+type Ticks = Int
+tick_freq = 50 :: Ticks -- accuracy of threadDelay (ticks per sec)
+tick_usecs = 1000000 `quot` tick_freq :: Int
+
+newtype CTimeVal = CTimeVal ()
+
+foreign import ccall unsafe "sizeofTimeVal"
+ sizeofTimeVal :: Int
+
+foreign import ccall unsafe "getTicksOfDay"
+ getTicksOfDay :: IO Ticks
+
+foreign import ccall unsafe "setTimevalTicks"
+ setTimevalTicks :: Ptr CTimeVal -> Ticks -> IO ()
+
+-- ----------------------------------------------------------------------------
+-- select() interface
+
+-- ToDo: move to System.Posix.Internals?
+
+newtype CFdSet = CFdSet ()
+
+foreign import ccall safe "select"
+ c_select :: Fd -> Ptr CFdSet -> Ptr CFdSet -> Ptr CFdSet -> Ptr CTimeVal
+ -> IO CInt
+
+foreign import ccall unsafe "hsFD_CLR"
+ fdClr :: Fd -> Ptr CFdSet -> IO ()
+
+foreign import ccall unsafe "hsFD_ISSET"
+ fdIsSet :: Fd -> Ptr CFdSet -> IO CInt
+
+foreign import ccall unsafe "hsFD_SET"
+ fdSet :: Fd -> Ptr CFdSet -> IO ()
+
+foreign import ccall unsafe "hsFD_ZERO"
+ fdZero :: Ptr CFdSet -> IO ()
+
+foreign import ccall unsafe "sizeof_fd_set"
+ sizeofFdSet :: Int
+
+#endif
\end{code}
projects / haskell-directory.git / blobdiff